Logging with jdk1.4 - how to add a handler using configuration file

Question

Hi, all
I am playing around with java.util.logging in jdk1.4. In particular, I am using a properties file for configuration. However, one thing I couldn't do is to assign a handler, such as the ConsoleHandler, to the com.xyz.foo logger. Everything for the root logger works just fine. Here's the file I use
handlers= java.util.logging.FileHandler
.level= INFO
java.util.logging.FileHandler.pattern = jdk14.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
java.util.logging.ConsoleHandler.level = INFO
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
com.xyz.foo.level = WARNING
com.xyz.foo.handlers = java.util.logging.ConsoleHandler
Nothing comes out on the console and everything from the com.xyz.foo logger is logged to jdk14.log file.
Can any one tell me why the last line has no effect?
Thanks much!

Answer 1

Logger configuration files are grossly misunderstood due in large part to extremely poor documentation (some of the worst I have ever seen for the Java platform). The LogManager class uses logger configuration files to do three things:
1. Load porperties into a private Properties object that application programmers can subsequently access using the getProperty(String name) method in LogManager.
2. Those properties (or else the documented defaults) are then used to configure the root logger as well as the "global" handlers that are used by the root logger
3. Finally, whenever a logger is created the Properties object is checked to see if a key exists for the logger name + ".limit". If so, then the logger is assigned that level.
Notice that nowhere in here does it say that a programmatically created logger is configured. In your case, you must invoke getProperty("com.xyz.foo.handlers"), parse the property value (which is a bit tricky if there is more than one handler class name), load and instantiate the handler class, and invoke addHandler. Great huh? I'm in the middle of a indepth study of logger configuration, and I can tell you for sure the static configuration using configuration files is an order of magnitude harder than dynamic configuration. It offers the advantage of field service engineers being able to change the logger configuration, but at a very significant cost.